.At this moment the bell rang the end of class.　A. announce　B. announcing　C. announced　D.

问题补充：

.At this moment the bell rang the end of class.

A. announce

B. announcing

C. announced

D. to announce

答案：

A. announce

(答案→)B. announcing

C. announced

D. to announce

解析：考察非谓语动词.句意:就在这时铃声响了,宣布了这一刻的结束 .现在分词表示主语正在进行的 伴随性动作,和句子主语是主谓关系.故选B.